Many instrument panel beams are configured as formed tubular steel structures having depending struts extending transversely therefrom, as well as extending from auxiliary structures attached to the formed tubular steel structures. Steel structures tend to be relatively heavy, so in order to reduce vehicle weight in order to enhance fuel consumption, some instrument panel beams are currently being cast from aluminum-magnesium (Al—Mg) alloys that weigh substantially less than steel beams. Since Al—Mg alloys are more expensive than steel, there is a need to take advantage of weight savings provided by cast Al—Mg beams, while reducing the cost thereof by optimizing Al—Mg mass. Moreover, there is a need to provide an Al—Mg instrument panel beam that is compatible with existing automotive body and frame configurations in a way that the weight advantages of Al—Mg alloy castings can be conveniently employed in existing vehicle designs.